What makes a lemon?

[RJSATLBA]

Here is a question for the engineers (be they mechanical, electrical or software) on the forum. It isn't a question for the lawyers!

There seems to be an acceptance of a relatively high level of problems due to bleeding edge technology and I should have thought that most of that would be in the electronics that controls and integrates the components rather than in the components themselves, perhaps with the exception of the use of CFRP.

Software isn't like hardware, there should not be variations due to manufacturing tolerances. So, if software releases are properly controlled so there aren't many different versions out there at once, I've been wondering how can some cars be lemons and other cars be fine.

It seems to me that the variability must be down to:

- manufacturing defects/tolerances (which can only be fixed by design/process change, not by software changes except to the extent that the software can reduce the load/stress on the component by imposing operational limits, such as with the KLE)
- different spec permutations, whether due to buyers' choices or national differences, although this could account for the software working fine on some cars but not on others
- different user controlled settings on otherwise identical cars
- environment factors
- users' 'habits'

Does this make sense?

[Edited to add 'user settings']

 

[jackt]

Though the software can be controlled pretty well, there are a lot of variations even with the i3 small set of extras (compared to other BMWs)

I think much of the problems at least what I have experience or seen are centred around cooling, so theres a couple of variations of that system:

1) HP + Air Flap
2) HP + No Air Flap
3) No HP + No Air Flap + REX
4) No HP + Air Flap + REX

The same bit of coolant regulation code has to handle all 4 cases, and non of the setups are trivial and you also have to bare in mind that all 4 are on a fast moving box on wheels...

You can test software for years and its only until its really used by paying customers that you'll find some problems, they'll always find a way to use things that the original engineers didn't consider.

I also think some of the reported Lemons' are down to a poor dealers who cannot turn around problems quick enough because their techs aren't yet comfortable with the "different" bits. That said even the Germans sometimes make a bad car... (heresy I know )

*For the record mine has a leak in the AC, which is going to be addressed soon. My dealer was pretty for coming in the fact they didn't have the appropriate coolant workstation to be able to service this yet.